Re: [Gretl-devel] Re: [Gretl-users] reversing / flipping a matrix
On Fri, 10 Jul 2009, Riccardo (Jack) Lucchetti wrote:
On Fri, 10 Jul 2009, Sven Schreiber wrote:
> I agree that two separate functions would not be good. What I meant was
> something like:
>
> rev(A,1) -- reverses row-wise
> rev(A,2) -- reverses col-wise (or maybe rev(A,'c'))
> rev(A) -- defaults to /alias for rev(A,1)
This may make sense, with a slight modification: instead of 1/2,
I'd rather use 0/1, so it becomes easy to decide on a logical
condition (eg. rev(A, foo>bar)). Besides, reversing columns
would probably be more CPU-efficient, since we could use
memcpy() for that, as in ... [C code snipped]
I agree (and support using the 0/1 flag). I'm adding the
column-reversal code to CVS for testing (though it looks fine).
One small thing: "rev" strikes me as kinda cryptic. If it's
standard usage elsewhere then maybe it's OK, but otherwise I'd
prefer something a bit more explicit, say "mreverse".
Allin.